50 If you will not learn Who Christ is from those that know Him, learn it at least from those that know Him not. So shall the confession, which their ignorance is forced to make, rebuke your blasphemy. The Jews did not recognise Christ, come in the body, though they knew that the true Christ must be the Son of God. And so, when they were employing false witnesses, without one word of truth in their testimony, against Him, their priest asked Him, Are You the Christ, the Son of the Blessed ? They knew not that in Him the mystery was fulfilled; they knew that the Divine nature was the condition of its fulfilment.
They did not ask whether Christ be the Son of God; they asked whether He were Christ, the Son of God. They were wrong as to the Person, not as to the Sonship, of Christ. They did not doubt that Christ is the Son of God; and thus, while they asked whether He were the Christ, they asked without denying that the Christ is the Son of God. What, then, of your faith, which leads you to deny what even they, in their blindness, confessed? The perfect knowledge is this, to be assured that Christ, the Son of God, Who existed before the worlds, was also born of the Virgin.
Even they, who know nothing of His birth from Mary, know that He is the Son of God. Mark the fellowship with Jewish wickedness in which your denial of the Divine Sonship has involved you! For they have put on record the reason of their condemnation:— And by our Law He ought to die, because He made Himself the Son of God. Is not this the same charge which you are blasphemously bringing against Him, that, while you pronounce Him a creature, He calls Himself the Son? He confesses Himself the Son, and they declare Him guilty of death: you too deny that He is the Son of God.
What sentence do you pass upon Him? You have the same repugnance to His claim as had the Jews. You agree with their verdict; I want to know whether you will quarrel about the sentence. Your offense, in denying that He is the Son of God, is exactly the same as theirs, though their guilt is less, for they sinned in ignorance. They knew not that Christ was born of Mary, yet they never doubted that Christ must be the Son of God. You are perfectly aware of the fact that Christ was born of Mary, yet you refuse Him the name of Son of God.
If they come to the faith, there awaits them an un-imperilled salvation, because of their past ignorance. Every gate of safety is shut to you, because you persist in denying a truth which is obvious to you. For you are not ignorant that He is the Son of God; you know it so well that you allow Him the name as a title of adoption, and feign that He is a creature adorned, like others, with the right to call Himself a Son. You rob Him, as far as you can, of the Divine nature; if you could, you would rob Him of the Divine name as well. But, because you cannot, you divorce the name from the nature; He is called a Son, but He shall not be the true Son of God.
Source: On the Trinity (New Advent)